INTERNATIONAL PROFESSIONAL COMMUNITY
CIRCADIAN BODY CLOCK AND ARTIFICIAL LIGHTING
Circadian Biological Clock and Artificial Lighting
Second only to light from natural sources, we are exposed to artificial light sources in our daily activities. The widespread application of artificial lighting everywhere we go with longer working hours in the office, has drastically increased our exposure to the effects of artificial ‘daylight’ lighting at night-time. In particular, newer emerging LED technology has higher blue-light content over traditional incandescent and fluorescent, especially with Correlated Colour Temperatures (CCT) ≥ 5000˚K. For example, 5000˚K to 5500˚K appears similar to noon daylight.
Artificial light can vary from warm colours to cool colours depending on the light source colour temperature. It is fairly well established that warm-CCT light at night encourages melatonin production in humans and induces sleep and a restful night. On the other hand, blue-rich cooler-CCT lighting in the morning suppresses melatonin and leads to alertness and increased productivity.
Exposure to blue-rich cooler-CCT lighting during the circadian night has been shown to increase alertness as the melanopsin photoreceptors are sensitive to a range of wavelengths and reach peak light absorption at blue light wavelengths around 480nm. Previous studies have shown that blue light, which peaks close to the spectral sensitivity of the circadian system, can have night-time alerting effects on humans. Research has established a functional relationship between nocturnal blue light exposure and alertness and shown that this light can affect biomarkers, performance and subjective sleepiness.
The lamps referred to in the 'Lighting Solutions' section have been designed to match the circadian cycle via a ‘tunable light engine’ to produce cool-CCT and warm-CCT light at different times of the day and night.
Additionally, reducing ‘power per unit area per unit wavelength’ of the illumination of the short-wavelength blue light of the lamp's LED light source. The benefit is that, at night-time if really needed, the person can use artificial daylight (cool-CCT light) for reading as the amount of blue light contribution is considerably suppressed, which may help to reduce the trigger of night-time alerting effects and sleep loss. When reading, daylight provides much better contrast for seeing details over warm-CCT light but for general use it is always much better to use warm-CCT light at night-time.